Comparison of utilized coefficient of friction during different walking tasks in persons with and without a disability

The purpose of this study was to determine if older persons with a disability have greater utilized coefficient of friction requirements than healthy older and younger adults during various walking conditions. Forty-eight community-dwelling adults were divided into five groups based on medical diagnosis and age: CVA (unilateral stroke; mean age 63 years), DM (diabetes mellitus; mean age 70 years), ARTH (lower extremity arthritis; mean age 69 years), SENIOR (healthy; mean age 73 years), and YOUNG (healthy; mean age 29 years). Ground reaction forces (GRF) were recorded as subjects walked across a walkway, ascended and descended stairs, and negotiated a turn. The utilized coefficient of friction (COF_U) throughout stance was calculated as the ratio of shear to vertical GRFs, and the peak COF_U resulting from a shear force that would contribute to a forward foot slip was identified. Separate one-way ANOVAs were used to identify differences in peak COF _U across subject groups for each walking task. The results of this study found that for all conditions evaluated, those with a disability did not demonstrate greater friction requirements then adults without a disability. Friction requirements for the YOUNG group were significantly greater than all disability groups while negotiating a turn, and were greater than the DM group during level walking. These results indicated that the diagnostic groups evaluated in this study are not at any greater risk for slip initiation than the healthy older or younger adults during the tasks evaluated.